Leonard P. Rybak, MD, PhD

Research Professor, Department of Otolaryngology Head and Neck Surgery
(ENT) Otolaryngology- Head and Neck Surgery

    About me

    Dr. Leonard P. Rybak is a research professor and ear, nose and throat specialist whose general otolaryngology practice focuses on sinus disease and obstructive sleep apnea. Dr. Rybak received his medical degree from the Medical College of Wisconsin-Milwaukee and completed his internship at Hennepin County Medical Center in Minneapolis. He completed a residency in otolaryngology and also obtained a PhD at the University of Minnesota-Minneapolis.

    Dr. Rybak served as an assistant professor of otolaryngology at the University of Minnesota prior to coming to the SIU School of Medicine. Dr. Rybak's professional affiliations include the American College of Surgeons, and the American Academy of Otolaryngology - Head and Neck Surgery. Locally, he is a member of the Sangamon County Medical Society and of various committees at St. John’s Hospital and the SIU School of Medicine. He serves as president of the Sangamon County Chapter of the Society for Neuroscience.

    As a clinician and surgeon, Dr. Rybak's special interests include general otolaryngology and sleep apnea. Known both nationally and internationally for his research in the field of otolaryngology, Dr. Rybak has published and presented numerous articles and chapters dealing with various aspects of ear, nose and throat diseases. He is certified by the American Board of Otolaryngology.

    Research Interests/Areas of Expertise:

    • Growth of cochlear hair cells derived from Immortomouse (HEI-OC1, OC-k3 cells) in culture
    • Ototoxicity of cisplatin, carboplatin and loop diuretics and chemoprevention
    • Mechanisms controlling free radical production within the cochlea
    • Auditory development and ototoxicity during development
    • Scanning and transmission electron microscopy of the cochlea
    • Mechanisms of noise-induced hearing loss and pharmacological prevention
    • Cell death and cell replacement pathways in the cochlea



    Education & training

    Board Certifications
    Medical School
    Medical College of Wisconsin, Milwaukee, WI
    University of Minnesota, Minneapolis, MN - Otolaryngology

    Clinical locations


    SIU Ear, Nose & Throat (ENT)

    720 N. Bond Street Springfield , IL 62702
    Mon - Thu: 8:00 am-4:30 pm
    Fri: 8:30 am-4:30 pm

    Hospital privileges

    • HSHS St. John's Hospital, Springfield, IL
    • Memorial Health, Springfield IL


    Research Interests
    Sinusitis, Sleep Apnea, Thyroid Cancer, and Pediatric Otolaryngology